Apparatus for analyzing depth of holographic image and analyzing method thereof

ABSTRACT

Disclosed is an apparatus of analyzing a depth of a holographic image according to the present disclosure, which includes an acquisition unit that acquires a hologram, a restoration unit that restores a three-dimensional holographic image by irradiating the hologram with a light source, an image sensing unit that senses a depth information image of the restored holographic image, and an analysis display unit that analyzes a depth quality of the holographic image, based on the sensed depth information image, and the image sensing unit uses a lensless type of photosensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to Korean PatentApplication Nos. 10-2020-0170783, filed on Dec. 8, 2020, and10-2021-0039486, filed on Mar. 26, 2021, respectively, in the KoreanIntellectual Property Office, the disclosures of which are incorporatedby reference herein in their entireties.

BACKGROUND

Embodiments of the present disclosure described herein relate toanalysis of a holographic image, and more particularly, relate to anapparatus for analyzing a depth of a holographic image, and a method foranalyzing a depth of a holographic image.

A holographic display technology is a technology that reproduces thewavefront caused by an object by using a diffraction and interferenceprinciple of light, and makes the object appear as if it actually existsto observer's eyes. In particular, unlike the conventional stereo-typepseudo-hologram, the holographic display technology does not haveaccommodation-convergence mismatch, so there is no dizziness ordiscomfort caused by moving a viewpoint, thus it may be considered asthe ultimate hologram reproduction technology.

In the current industry, for the realization of an ideal holographicdisplay, the focus is on the development of display devices, theproduction of holographic contents, and the fast processing speed.However, there is still a long way to go in research for qualityanalysis of holographic images for final commercialization.

To measure a depth of the previously developed holographic image, amethod of acquiring a three-dimensional image with a lens array and animage sensor is used. Since this method uses a lens optical system,there is a physical limitation when measuring a very deep depth, and itis difficult to freely change the focal length. Accordingly, the presentdisclosure intends to present an apparatus for analyzing a depth of a 3Ddigital hologram image capable of easily changing the focal length.

SUMMARY

Embodiments of the present disclosure provide an apparatus for measuringa depth of a restored 3D holographic image for quality analysis of aholographic display in which a focal length can be freely changed.

According to an embodiment of the present disclosure, an apparatus ofanalyzing a depth of a holographic image includes an acquisition unitthat acquires a hologram, a restoration unit that restores athree-dimensional holographic image by irradiating the hologram with alight source, an image sensing unit that senses a depth informationimage of the restored holographic image, and an analysis display unitthat analyzes a depth quality of the holographic image, based on thesensed depth information image, and the image sensing unit uses alensless type of photosensor.

According to an embodiment, the image sensing unit may include aphotosensor panel that measures the holographic image restored by therestoration unit, and an electric rail that moves the photosensor panelin a depth direction of the holographic image.

According to an embodiment, the depth direction of the holographic imagemay correspond to a direction of a spatial light modulator of therestoration unit from the photosensor panel.

According to an embodiment, the image sensing unit may include aplurality of transparent plane photosensors that measures theholographic image restored by the restoration unit, and at least oneelectric rail that moves the plurality of transparent plane photosensorsin a depth direction of the holographic image.

According to an embodiment, the plurality of transparent planephotosensor may include a first transparent plane photosensor that movesin a depth direction of a first region of a holographic space in whichthe restored holographic image is displayed, and a second transparentplane photosensor that moves in a depth direction of a second region ofthe holographic space.

According to an embodiment, the first region and the second region maynot overlap each other.

According to an embodiment, the apparatus may further include an imagetransmission unit that sequentially transmits the depth informationimage sensed by the image sensing unit in real time, and an imagegenerating unit that three-dimensionally restores the transmitted depthinformation image in a depth axis direction.

According to an embodiment, the analysis display unit may compare thedepth information image with depth information of an original imageassociated with an object, and may analyze a depth reproduction qualitybased on the comparison result.

According to an embodiment, the restoration unit may include a laserunit that generates a laser and provides the generated laser as thelight source, a collimator that outputs the generated laser as anenlarged plane wave, a spatial light modulator that reflects lightmodulated by the plane wave into a space when the enlarged plane wave isincident, and a beam splitter that changes and propagates at least aportion of the light reflected from the spatial light modulator in a setdirection.

According to an embodiment of the present disclosure, a method ofanalyzing a depth of a holographic image includes acquiring a hologramusing RGB brightness information and 3D stereoscopic information on anobject, restoring a three-dimensional holographic image by irradiatingthe hologram with a light source, sensing a depth information image foreach position in a holographic space in which the restored holographicimage is displayed, restoring a three-dimensional image including adepth axis direction in real time using the sensed depth informationimage for each position, and comparing the restored 3D image includingthe depth axis direction with a depth of an original image correspondingto the object, and analyzing a depth quality based on the comparisonresult.

According to an embodiment, the sensing of the depth information imagefor each position may be performed by using a photosensor panel thatmeasures the restored holographic image while moving in the depth axisdirection in the holographic space.

According to an embodiment, the sensing of the depth information imagefor each position may be performed by using a plurality of transparentplane photosensors that measure the restored holographic image whilemoving in the depth axis direction in the holographic space.

According to an embodiment, each of the plurality of transparent planephotosensors may move in the depth axis direction within a designatedregion.

BRIEF DESCRIPTION OF THE FIGURES

The above and other objects and features of the present disclosure willbecome apparent by describing in detail embodiments thereof withreference to the accompanying drawings.

FIG. 1 is a block diagram schematically illustrating an apparatus foranalyzing a depth of a holographic image according to an embodiment ofthe present disclosure.

FIG. 2 is a block diagram schematically illustrating an input/outputrelationship of an acquisition unit of FIG. 1.

FIG. 3 is a diagram illustrating a restoration unit of FIG. 1 by way ofexample.

FIG. 4 is a diagram illustrating a 3D hologram image restored through aspatial light modulator.

FIG. 5 is a diagram illustrating an image sensor unit of the presentdisclosure.

FIG. 6 is a diagram illustrating a sensing operation at a specificposition of a photosensor panel in an image sensor unit of the presentdisclosure.

FIG. 7 is a diagram illustrating a sensing operation at a specificposition of a photosensor panel in an image sensor unit of the presentdisclosure.

FIG. 8 is a diagram illustrating a sensing operation at a specificposition of a photosensor panel in an image sensor unit of the presentdisclosure.

FIG. 9 is a diagram illustrating an image sensor unit according toanother embodiment of the present disclosure.

FIG. 10 is a flowchart schematically illustrating a method for analyzinga depth of a holographic image according to an embodiment of the presentdisclosure.

FIG. 11 is a diagram schematically illustrating a method for analyzing adepth of a holographic image according to the present disclosure.

DETAILED DESCRIPTION

It is to be understood that both the foregoing general description andthe following detailed description are examples, and it is intended thatan additional description of the claimed disclosure is provided.Reference numerals are indicated in detail in preferred embodiments ofthe present disclosure, examples of which are indicated in the referencedrawings. Wherever possible, the same reference numerals are used in thedescription and drawings to refer to the same or like parts.Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings such that those skilled inthe art may easily carry out the present disclosure.

FIG. 1 is a block diagram schematically illustrating an apparatus foranalyzing a depth of a holographic image according to an embodiment ofthe present disclosure. Referring to FIG. 1, a holographic image depthanalysis apparatus 100 according to an embodiment of the presentdisclosure includes an acquisition unit 110, a restoration unit 120, animage sensor unit 130, an image transmission unit 140, an imagegenerating unit 150, and an analysis display unit 160.

The acquisition unit 110 may acquire a hologram through computercalculation or directly through an optical method. In this case, theacquisition unit 110 may receive RGB (Red, Green, and Blue) brightnessinformation and 3D stereoscopic information on an object (a subject),and may acquire the hologram through computer calculation based on inputinformation, or may directly acquire the hologram through the opticalmethod. For example, as illustrated in FIG. 2 to be described later, asthe input information, the acquisition unit 110 may receive the RGBbrightness information of a three-dimensional object and various typesof three-dimensional information such as a depth map, point cloud data,or a three-dimensional mesh model-based data. The acquisition unit 110may generate a digital hologram by performing a computer calculationusing the input stereoscopic information.

The restoration unit 120 irradiates the acquired hologram with a lightsource such as laser, an LED (Light Emitting Diode), or white light tooptically restore a three-dimensional holographic image (i.e., areproduction image of the hologram). For optical restoration of thedigital hologram, the restoration unit 120 may include, for example, alight source unit generating the light source such as the laser or theLED, a spatial light modulator (SLM), and an optical system such as alens and a mirror.

The image sensor unit 130 includes a photosensor panel that measures therestored hologram region in a space and an electric rail that preciselymoves the photosensor panel in the space. The photosensor panel is anear-focus sensor display of a lensless type, and its array may becomposed of elements that record information of a light source incidentfrom the outside. The recording elements are required to have a highpixel density (PPI: Pixel Per Inch) and a large area so as to acquireimages with high precision and a wider range. To implement this, thephotosensor panel may be configured with a large-area high-resolutionsensor image array formed on a glass substrate. The photosensor panelmay be provided in a lensless type so that only holographic informationclose to the sensor may be recognized. By moving the photosensor paneldirectly in a direction of the light modulator as much as a sensormovement distance (a depth of a hologram region), the depth informationimage for each position may be sensed. In addition, in anotherembodiment, the image sensor unit 130 may arrange a plurality oftransparent photosensor panels in a holographic space. In thisembodiment, since several photosensor panels are used at once, the timerequired for moving the sensor may be shortened.

The image transmission unit 140 sequentially transmits the holographicspatial images obtained by the image sensor unit 130 to the imagegenerating unit 150. The image transmission unit 140 transfers theobtained holographic spatial images from an output port of the imagesensor unit 140 to an input port of the image generating unit 150 inreal time. In this case, the input port enables transmission ofinformation by using a wired/wireless protocol port embedded in a mobilephone, a tablet, or a laptop computer in addition to a PC.

The image generating unit 150 restores the holographic spatial imagestransmitted in real time in three dimensions in a depth axis direction.The image generating unit 150 may provide the restored holographicspatial images to the analysis display unit 160.

The analysis display unit 160 may analyze a depth reproduction qualityof the holographic image, based on the measured depth of the holographicimage. In this case, the analysis display unit 160 may compare themeasured depth of the holographic image with a depth of an originalimage associated with the object, and may analyze the depth reproductionquality based on the comparison result. The analysis display unit 160may obtain a relationship between an original depth and the measurementdepth, and may analyze results such as linear/nonlinear characteristicsin the depth axis direction, a depth reproduction accuracy of therestored image depending on a position in a horizontal-vertical axisdirection, the depth reproduction accuracy depending on an observationangle, a depth resolution for each depth. In addition, from the result,it is possible to evaluate hologram signal processing algorithm such ashologram generation and compression/encoding, an optical acquisitionenvironment of a hologram, and a holographic display system. Theanalysis display unit 160 analyzes factors that cause qualitydeterioration based on the evaluation result, so that it can beeffectively utilized for quality improvement. The analysis display unit160 may display the analysis result on a display.

The holographic image depth analysis apparatus 100 according to anembodiment of the present disclosure described above may measure thedepth of a 3D stereoscopic reproduced image restored optically from thehologram. In addition, by comparing the measured depth information ofthe 3D stereoscopic image with the depth information of the 3D originalobject, it is possible to objectively evaluate the depth reproductionquality of the hologram. In particular, since the image sensor unit 130may measure the depth of the 3D holographic image in a lensless type,there is little physical limitation and a focal length may be freelychanged.

FIG. 2 is a block diagram schematically illustrating an input/outputrelationship of an acquisition unit of FIG. 1. Referring to FIG. 2, theacquisition unit 110 may receive RGB brightness information and 3Dspatial information of a 3D object, and may calculate a digital hologramthat is fringe pattern data using a computer-generated hologram (CGH)method. In this case, the 3D spatial information may be a depth map,point cloud data, or 3D mesh model data.

FIG. 3 is a diagram illustrating a restoration unit of FIG. 1 by way ofexample. Referring to FIG. 3, the restoration unit 120 in an apparatusfor measuring a quality of the holographic image is an apparatus capableof optically restoring the hologram, and may include a laser 121, acollimator 123, a beam splitter 125, and a spatial light modulator 127(SLM).

The laser 121 may generate a laser and may irradiate the hologram. Inthis case, the hologram may exist at a position of the spatial lightmodulator SLM.

The collimator 123 may output the generated laser as an enlarged planewave.

The spatial light modulator 127 may be a display that reproduces thehologram, and when a plane wave output from the collimator 123 passesthrough the beam splitter 125 and is incident, may reflect lightmodulated from the incident plane wave into the space.

The beam splitter 125 may transmit the output plane wave and maytransfer it to the spatial light modulator 127. In addition, the beamsplitter 125 may separate at least a portion of the light reflected fromthe spatial light modulator 127 by changing the direction to form animage at a desired position, thereby restoring the holographic image129.

FIG. 4 is a diagram illustrating a 3D hologram image restored through aspatial light modulator. Referring to FIG. 4, a computer generatedhologram (hereinafter, CGH) restored by the spatial light modulator 127may be displayed in the holographic space.

A three-dimensional CGH image with a sense of depth restored by thespatial light modulator 127 is positioned between an observer and an SLMpanel constituting the spatial light modulator 127. The observer may seethis image from a front of the panel and may feel the spatial sense ofthe front and back images as the viewpoint moves. The 3D image may bedifferentially expressed depending on the panel performance of thespatial light modulator 127 and a configuration of an optical device.

FIG. 5 is a diagram illustrating an image sensor unit of the presentdisclosure. Referring to FIG. 5, the image sensor unit 130 (refer toFIG. 1) includes a photosensor panel 132 that measures a holographicimage expressed in the holographic space, and an electric rail (notillustrated) that precisely moves the photosensor panel 132.

The three-dimensional CGH image restored by the spatial light modulator127 is displayed on the holographic space. In addition, the photosensorpanel 132 may move to measure a hologram region expressed on theholographic space. For this purpose, an electric rail that preciselymoves the photosensor panel 132 will be driven.

The photosensor panel 132 is the near-focus sensor display of thelensless type, and may be composed of an array of elements that recordinformation of the light source incident from the outside. Theserecording elements are required to have a high pixel density (PPI: PixelPer Inch) and a large area so as to acquire images with high precisionand a wider range. Accordingly, to satisfy this condition, thephotosensor panel 132 may be configured with a large-areahigh-resolution sensor image array formed on a glass substrate. Thephotosensor panel 132 is configured in a lensless manner so that onlyholographic information close to the sensor may be recognized. Inparticular, the photosensor panel 132 may sense the depth informationimage at each of a plurality of positions while the photosensor panel132 directly moves in a direction (z-axis direction) of the spatiallight modulator 127 as much as the sensor movement distance (the depthof the hologram region).

FIG. 6 is a diagram illustrating a sensing operation at a specificposition of a photosensor panel in an image sensor unit of the presentdisclosure. Referring to FIG. 6, the image sensor unit 130 (refer toFIG. 1) may precisely move the photosensor panel 132 from an initialposition ‘A’ to a next sensing position ‘B’ in the holographic spaceusing the electric rail.

The photosensor panel 132 moves from the initial position ‘A’ in thedirection (z-axis direction) of the spatial light modulator 127. Inparticular, the photosensor panel 132 maintains the same position as inthe position ‘A’ with respect to the ‘x’ and ‘y’ axes at the positionThe photosensor panel 132 will sense the depth information image of theCGH image restored from the moved position

FIG. 7 is a diagram illustrating a sensing operation at a specificposition of a photosensor panel in an image sensor unit of the presentdisclosure. Referring to FIG. 7, the image sensor unit 130 (refer toFIG. 1) may precisely move the photosensor panel 132 from the position‘B’ to a next sensing position ‘C’ in the holographic space using theelectric rail.

The photosensor panel 132 moves in the direction (z-axis direction) ofthe spatial light modulator 127 from the previous sensing position Inparticular, the photosensor panel 132 maintains the same position as atthe position ‘B’ with respect to the ‘x’ and ‘y’ axes at the position‘C’. The photosensor panel 132 will sense the depth information image ofthe CGH image restored from the moved position ‘C’.

FIG. 8 is a diagram illustrating a sensing operation at a specificposition of a photosensor panel in an image sensor unit of the presentdisclosure. Referring to FIG. 8, the image sensor unit 130 (refer toFIG. 1) may precisely move the photosensor panel 132 from the position‘C’ to a next sensing position ‘D’ in the holographic space using theelectric rail.

The photosensor panel 132 moves in the direction (z-axis direction) ofthe spatial light modulator 127 from the previous sensing position ‘C’.In particular, the photosensor panel 132 maintains the same position asat the position ‘C’ with respect to the ‘x’ and ‘y’ axes at the position‘D’. The photosensor panel 132 will sense the depth information image ofthe CGH image restored from the moved position ‘D’.

With reference to FIGS. 5 to 8, the movement of the photosensor panel132 constituting the image sensing unit 130 of the present disclosureand the sensing method of the depth information image at each of theplurality of moved positions have been described. The image sensing unit130 will sequentially transmit the holographic spatial images sensed ateach position to the image generating unit 150 through the imagetransmission unit 140. The image transmission unit 140 may transmit theholographic spatial images sensed for each position in real time.

FIG. 9 is a diagram illustrating an image sensor unit according toanother embodiment of the present disclosure. Referring to FIG. 9, theimage sensor unit 130 (refer to FIG. 1) may include a plurality oftransparent plane photosensors 133, 134, 135, and 136 that measure theholographic image expressed in the holographic space, and may include atleast one electric rail (not illustrated) that precisely moves each ofthe plurality of transparent plane photosensors 133, 134, 135, and 136.

The three-dimensional CGH image restored by the spatial light modulator127 is displayed on the holographic space. In addition, the plurality oftransparent plane photosensors 133, 134, 135, and 136 may move tomeasure the hologram region expressed in the holographic space. To thisend, the electric rail or actuators for precisely moving the pluralityof transparent plane photosensors 133, 134, 135, and 136 may be furtherincluded. Each of the plurality of transparent plane photosensors 133,134, 135, and 136 may be provided with a transparent photosensor panelformed of a transparent material. Accordingly, the 3D CGH image restoredfrom the spatial light modulator 127 may be displayed on the entireholographic space by passing through the transparent plane photosensors133, 134, 135, and 136.

The transparent plane photosensor 133 may move within an ‘A’ region bythe sensor movement distance allocated in the direction (z-axisdirection) of the spatial light modulator 127. The depth informationimage in the region ‘A’ may be sensed by the transparent planephotosensor 133. In this case, the distance that the transparent planephotosensor 133 moves is significantly reduced compared to the distancethat one photosensor panel 132 (refer to FIG. 5) moves, and the movingtime is also reduced depending on the reduction of the moving distanceof the sensor.

As in the above description, the transparent plane photosensor 134 is incharge of sensing the depth information image in a ‘B’ region. Since thetransparent plane photosensor 134 only needs to move within the ‘B’region, the moving time may be significantly reduced. The transparentplane photosensor 135 is in charge of sensing the depth informationimage in a ‘C’ region. In addition, the transparent plane photosensor136 is in charge of sensing the depth information image in a ‘D’ region.Since the transparent plane photosensors 135 and 136 also only need tomove within the ‘C’ region and the ‘D’ region, respectively, themovement time of the sensor may be remarkably reduced. Compared to thecase of measuring with only one photosensor panel, it takes only thetime divided by the number of transparent plane photosensors to move thesensor, so quick depth analysis will be possible. Therefore, it isexpected as a technology that will contribute to an industrialization ofthe light modulator display.

In this case, an example in which the four transparent planephotosensors 133, 134, 135, and 136 are dedicated to four regions in theholographic space to sense the depth information image has beendescribed, but the present disclosure is not limited thereto. The numberof transparent plane photosensors to be disposed may be determined inconsideration of the length of the holographic space or characteristicsor performance of the electric rail for driving the transparent planephotosensors.

FIG. 10 is a flowchart schematically illustrating a method for analyzinga depth of a holographic image according to an embodiment of the presentdisclosure. Referring to FIG. 10, a method for analyzing a depth of aholographic image using an image sensor unit using a position-movablephotosensor panel or a transparent plane photosensor according to thepresent disclosure will be described.

In operation S110, a holographic image is obtained by the holographicimage depth analysis apparatus 100. First, the acquisition unit 110(refer to FIG. 1) may acquire a hologram. In this case, the holographicimage depth analysis apparatus 100 may receive the RGB brightnessinformation and the 3D stereoscopic information on an object, and mayacquire the holographic image using the input RGB brightness informationand the input 3D stereoscopic information. In addition, the holographicimage depth analysis apparatus 100 may divide the beam into equal partsthrough the beam splitter, may transfer it to each of the object and themirror, and may acquire the hologram corresponding to an interferencepattern of the beam reflected from the object with respect to the beamreflected from the mirror through the camera.

In operation S120, the holographic image depth analysis apparatus 100may restore the three-dimensional holographic image by irradiating alight source to the hologram. In this case, the holographic image depthanalysis apparatus 100 may generate a laser as the light source throughthe laser unit, and output the generated laser as the enlarged planewave through the collimator. In addition, the holographic image depthanalysis apparatus 100 may modulate the plane wave when the enlargedplane wave is incident through the spatial light modulator SLM, mayreflect it into the space, and may restore the holographic image bychanging a direction of at least some of the modulated plane wavesreflected from the spatial light modulator SLM through the beam splitterand by propagating it into an empty space.

In operation S130, the holographic image depth analysis apparatus 100will sense the depth information image of the holographic image restoredfor each position in the holographic space. In this case, the imagesensor unit 130 (refer to FIG. 1) may precisely move the photosensorpanel 132 in the holographic space by using the electric rail. Inaddition, the sensed holographic depth information image for eachposition will be transmitted to the image generating unit 150 in realtime by the image transmission unit 140.

In operation S140, the holographic image depth analysis apparatus 100generates the three-dimensional image in real time by using theholographic depth information image for each position in the holographicspace. The image generating unit 150 (refer to FIG. 1) restores theholographic spatial images transmitted in real time in the depth axisdirection in three dimensions. The image generating unit 150 may providethe restored holographic spatial images to the analysis display unit160.

In operation S150, the analysis display unit 160 may analyze the depthquality of the holographic image, based on the measured depth of theholographic image. In this case, the analysis display unit 160 maycompare the measured depth of the holographic image with the depth ofthe original image associated with the object, and may analyze the depthquality based on the comparison result. The analysis display unit 160may obtain a relationship between the original depth and the measurementdepth, and may analyze results such as linear/nonlinear characteristicsin the depth axis (z-axis) direction, a depth reproduction accuracy ofthe restored image depending on a position in a horizontal-vertical axisdirection, the depth reproduction accuracy depending on an observationangle, a depth resolution for each depth. In addition, from the result,it is possible to evaluate hologram signal processing algorithm such ashologram generation and compression/encoding, an optical acquisitionenvironment of the hologram, and a holographic display system. Theanalysis display unit 160 analyzes factors that cause qualitydeterioration based on the evaluation result, so that it can beeffectively utilized for quality improvement. The analysis display unit160 may display the analysis result on the display.

FIG. 11 is a diagram schematically illustrating a method for analyzing adepth of a holographic image according to the present disclosure.Referring to FIG. 11, the image for depth analysis may be sensed andtransmitted in real time by the image sensor unit using the movablephotosensor panel 132 or the transparent plane photosensor 133, 134,135, and 136 of the present disclosure.

The holographic image depth analysis apparatus 100 (refer to FIG. 1)will sense the depth information image of the holographic image restoredfor each position in the holographic space. In this case, the imagesensor unit 130 (refer to FIG. 1) may precisely move the photosensorpanel 132 or the transparent plane photosensors 133, 134, 135, and 136in the holographic space by using the electric rail. In addition, thesensed holographic depth information image for each position (theposition ‘A’ to a position ‘N’) will be transmitted to the imagegenerating unit 150 in real time by the image transmission unit 140.

A real-time three-dimensional image generating apparatus illustrated asan example of the image generating unit 150 generates thethree-dimensional image in real time by using the holographic depthinformation image for each position in the holographic space. Thereal-time 3D image generating apparatus restores the holographic spatialimages transmitted in real time in the direction of the depth axis inthree dimensions. The image generating unit 150 may provide the restoredholographic spatial images to the analysis display unit 160.

The analysis display unit 160 may analyze the depth quality of theholographic image based on the measured depth of the holographic image.In this case, the analysis display unit 160 may compare the measureddepth of the holographic image with the depth of the original imageassociated with the object, and may analyze the quality of the sense ofdepth based on the comparison result. The analysis display unit 160 mayobtain a relationship between the original depth and the measurementdepth, and may analyze results such as linear/nonlinear characteristicsin the depth axis (z-axis) direction, a depth reproduction accuracy ofthe restored image depending on a position in a horizontal-vertical axisdirection, the depth reproduction accuracy depending on an observationangle, a depth resolution for each depth. In addition, from the result,the hologram signal processing algorithm such as hologram generation andcompression/encoding, an optical acquisition environment of thehologram, and a holographic display system may be evaluated. Theanalysis display unit 160 may display the analysis result on thedisplay.

The apparatus described above may be implemented as a hardwarecomponent, a software component, and/or a combination of the hardwarecomponent and the software component. For example, devices andcomponents described in the embodiments may be implemented using, forexample, one or more general purpose or special purpose computers, suchas a processor, a controller, an arithmetic logic unit (ALU), a digitalsignal processor, a microcomputer, a field programmable array (FPA), aprogrammable logic unit (PLU), a microprocessor, or any other devicecapable of executing and responding to instructions. The processingdevice may execute operating system (OS) and one or more softwareapplications running on the operating system. The processing device mayalso access, store, manipulate, process, and generate data in responseto execution of the software. For convenience of understanding, althoughone processing device is sometimes described as being used, one ofordinary skill in the art will recognize that the processing deviceincludes a plurality of processing elements and/or a plurality of typesof processing elements. For example, the processing device may include aplurality of processors or one processor and one controller. Otherprocessing configurations are also possible, such as parallelprocessors.

Software may include a computer program, a code, instructions, or acombination of one or more of these, may configure a processing deviceto operate as desired, and may independently or collectively command theprocessing device. The software and/or data may be permanently ortemporarily embodied in any kind of machine, a component, a physicaldevice, a virtual equipment, a computer storage medium or device, atransmitted signal wave to be interpreted by or to provide instructionsor data to the processing device. The software may be distributed overnetworked computer systems and may be stored or executed in thedistributed manner The software and data may be stored in one or morecomputer-readable recording media.

According to an embodiment of the present disclosure, the apparatus foranalyzing a depth of a three-dimensional holographic image may measurethe depth in a three-dimensional holographic image by using a lenslessmanner. In the method of using a lens, the sense of depth of theholographic display was evaluated by changing the focus of the lens.Since this typical method uses an optical lens, it is difficult toaccurately and quickly check the quality of a holographic displaybecause it is inevitable to configure an additional optical systemaccording to the lens periphery distortion and the distance between thedisplay and the camera. However, when photosensor panel and thetransparent photosensor panel having the lensless type as proposed inthe present disclosure are applied to the analysis device, theholographic space may be scanned in real time, and the sense of depthmay be measured more clearly and easily.

The contents described above are specific embodiments for implementingthe present disclosure. The present disclosure will include not only theembodiments described above but also embodiments in which a design issimply or easily capable of being changed. In addition, the presentdisclosure may also include technologies easily changed to beimplemented using embodiments. Therefore, the scope of the presentdisclosure is not limited to the described embodiments but should bedefined by the claims and their equivalents.

What is claimed is:
 1. An apparatus of analyzing a depth of aholographic image comprising: an acquisition unit configured to acquirea hologram; a restoration unit configured to restore a three-dimensionalholographic image by irradiating the hologram with a light source; animage sensing unit configured to sense a depth information image of therestored holographic image; and an analysis display unit configured toanalyze a depth quality of the holographic image, based on the senseddepth information image, and wherein the image sensing unit uses alensless type of photosensor.
 2. The apparatus of claim 1, wherein theimage sensing unit includes: a photosensor panel configured to measurethe holographic image restored by the restoration unit; and an electricrail configured to move the photosensor panel in a depth direction ofthe holographic image.
 3. The apparatus of claim 2, wherein the depthdirection of the holographic image corresponds to a direction of aspatial light modulator of the restoration unit from the photosensorpanel.
 4. The apparatus of claim 1, wherein the image sensing unitincludes: a plurality of transparent plane photosensors configured tomeasure the holographic image restored by the restoration unit; and atleast one electric rail configured to move the plurality of transparentplane photosensors in a depth direction of the holographic image.
 5. Theapparatus of claim 4, wherein the plurality of transparent planephotosensor includes: a first transparent plane photosensor configuredto move in a depth direction of a first region of a holographic space inwhich the restored holographic image is displayed; and a secondtransparent plane photosensor configured to move in a depth direction ofa second region of the holographic space.
 6. The apparatus of claim 5,wherein the first region and the second region do not overlap eachother.
 7. The apparatus of claim 1, further comprising: an imagetransmission unit configured to sequentially transmit the depthinformation image sensed by the image sensing unit in real time; and animage generating unit configured to three-dimensionally restore thetransmitted depth information image in a depth axis direction.
 8. Theapparatus of claim 1, wherein the analysis display unit compares thedepth information image with depth information of an original imageassociated with an object, and analyzes a depth reproduction qualitybased on the comparison result.
 9. The apparatus of claim 1, wherein therestoration unit includes: a laser unit configured to generate a laserand provide the generated laser as the light source; a collimatorconfigured to output the generated laser as an enlarged plane wave; aspatial light modulator configured to reflect light modulated from theplane wave into a space when the enlarged plane wave is incident; and abeam splitter configured to change a direction of at least a portion ofthe light reflected from the spatial light modulator and propagate thechanged light.
 10. A method of analyzing a depth of a holographic image,the method comprising: acquiring a hologram using RGB brightnessinformation and 3D stereoscopic information of an object; restoring athree-dimensional holographic image by irradiating the hologram with alight source; sensing a depth information image for each position in aholographic space in which the restored holographic image is displayed;restoring a three-dimensional image including a depth axis direction inreal time using the sensed depth information image for each position;and comparing the restored 3D image including the depth axis directionwith a depth of an original image corresponding to the object, andanalyzing a depth quality based on the comparison result.
 11. The methodof claim 10, wherein the sensing of the depth information image for eachposition is performed by using a photosensor panel that measures therestored holographic image while moving in the depth axis direction inthe holographic space.
 12. The method of claim 10, wherein the sensingof the depth information image for each position is performed by using aplurality of transparent plane photosensors that measure the restoredholographic image while moving in the depth axis direction in theholographic space.
 13. The method of claim 12, wherein, each of theplurality of transparent plane photosensors moves in the depth axisdirection within a designated region.